fix: minimizing with responsive extensions (#1406)

* fix: minimizing with responsive extensions

* fix: check if responsive size is default

Co-authored-by: Xiaotian Gu <[email protected]>

* chore: add test

---------

Co-authored-by: Xiaotian Gu <[email protected]>

Author: rajamatt

src/Uno.Toolkit.RuntimeTests/Tests/ResponsiveExtensionsTests.cs

@@ -160,6 +160,27 @@ public async Task ProvideValue_Orientation_SizeChange()
 		ext.ForceResponsiveSize(WideSize);
 		Assert.AreEqual(Orientation.Horizontal, sut.Orientation);
 	}
+
+	[TestMethod]
+	public async Task ProvideValue_ZeroSize_NoSizeChange()
+	{
+		var sut = XamlHelper.LoadXaml<TextBlock>("""
+			<TextBlock Text="{utu:Responsive Narrow=asd, Wide=qwe}" />
+		""");
+		var ext = ResponsiveExtension.GetInstanceFor(sut, nameof(sut.Text)) ?? throw new InvalidOperationException("Failed to resolve the markup extension.");
+		await UnitTestUIContentHelperEx.SetContentAndWait(sut);
+
+		ext.ForceResponsiveSize(WideSize);
+		Assert.AreEqual("qwe", sut.Text);
+
+		var previousResult = ext.LastResolved?.Result;
+		var previousSize = ext.LastResolved?.Size;
+
+		ext.ForceResponsiveSize(new Size(0, 0));
+
+		Assert.AreEqual(previousResult, sut.Text);
+		Assert.AreEqual(previousSize, ext.LastResolved?.Size);
+	}
 }
 
 [TestClass]

src/Uno.Toolkit.UI/Markup/ResponsiveExtension.cs

@@ -196,6 +196,7 @@ internal void Disconnect()
 
 	private void OnWindowSizeChanged(object sender, Size size)
 	{
+		if (size == default) return; // when the app is minimized
 		if (size == LastResolved?.Size) return;
 		if (CleanupIfHostDisposed())
 		{